Propeller blade



Feb. 27, 1945. H. A. BERLINER PROPELLER BLADE Filed Nov. 5, 1941 2Sheets-Sheet 1 Havoc/wh Henry A. Ber/ i797 Feb. 27, 1945. H. A. BERLJNER2,370,136

PROPELLER BLADE' Filed Ndv. 5, 1941 2 Sheets-Sheet 2 unluniannu-z. ..V

zjwvwm Henry A. Ber/me)" elty Patent e11! Feb. 27, 1945 PROPELLER' BLADEHenry A. Berliner, Washington, D. 0.,

Engineering 8: Reaearch Corporation,

aesignor to Riverdale, Md., a corporation'ot Maryland ApplicationNovember 5, 1941, Serial No. 417,951

1 Claim.

This invention relates to propeller blades and. more particularly, tohollow, metallic blades of a. type particularly adapted for use inaircraft.

The principal object of the invention is to provide a hollow, metallicpropeller blade having internal reinforcing members, which blade isformed by the simple operations of deiorm-' ing and attaching together aplurality 01 metal tubes or sheet metal members to provide elongatedparts which extend longitudinally of the blade. In carrying out thissimplified manner of construction any one of a number of combinations oftubular and sheet metal sections and parts may be used, and the blademay be formed of two or more of such sections and parts,

According to one important feature of the invention, the severalsections of the blade are formed of hollow tubes rigidly securedtogether longitudinally of the blade and shaped to give the blade thedesired cross-sectional configuration. According to another feature ofthe invention, one or more of the longitudinal sections of the blade isformed of a hollow tube, while one or more of the other longitudinalsectional parts of the blade may be formed of sheet metal or othersuitable material attached to the tubular section or sections, all ofthe parts being properly shaped to provide the desired cross-sectionalshape.

In a preferred form of the invention the blade is formed by a central,longitudinal tubular section having other longitudinal tubular sectionalparts attached to the side walls thereof to form the leading andtrailing edge portions of the blade. However, the invention contemplatesthat the blade may be formed of a lesser or greater number oflongitudinal sectional parts and that bent sheet metal parts may takethe place of the deformed tubular parts contemplated in the preferredembodiment.

Another principal object of the invention is to provide a blade which isvery simple and inexpensive in construction, and yet is strong and hasthe desired airflow shape throughout.

The above and other objects, features of novand advantages of theinvention will be apparent from the following description when read inconnection with the accompanying drawings, in which Fig. 1 is alongitudinal section through one form of tube used in forming a sectionof the blade;

Fig. 2 is a plan view of a completed blade formed from the tube of Fig.l and from other parts;

Figs. 3 to 'l are sections on the lines 3-3, 4-4, 5-5, 6-6,respectively, of Fig. 2;

Fig. 8 is a longitudinal section through a second form of tube used informing a blade in accordanee with the invention:

Fig. 11 is a view, similar to Fig. 10, showinga further modification ofthe invention.

The main body portion of the blade is formed from a hollow metal tube ofsubstantially constant external diameter throughout its length, as

shown in section in Fig. l, and indicated at l0. Adjacent one end thetube is formed with an annular shoulder i2, by which it may be securedin place in a hub. It will be noted that the walls of the tube taper inthickness from the hub end toward the outer end, being substantiallythinner at the outer end than at the hub.

In forming the blade, the tube III is flattened throughout the portionthereof removed from the shoulder ii to provide upper and lower faces I,which are relatively wide and which are connected by narrower edges it.As shown, the edges ii are substantially straight and flat, and becomenarrower toward the outer end of the blade, while the faces ll becomewider. It will also be noted from the sections shown in Figs. 4 to 7that the pitch or angle of the faces ll changes progressively throughoutthe length of the blade.

The blade is completed by a pair of tubular hollow edge structuressecured to the edges I! by welding or brazing, and extendingsubstantially throughout the flattened portion of the tube. One suchstructure, indicated at [8, is so shaped as to form the leading edge ofthe blade, and the other structure 20 is shaped to form the trailingedge of the blade. As is shown in Figs. 4 to 7, the contour of the bladeformed by the main tube Ill and the leading and trailing edge structuresis such as to provide a desired airflow shape at all points in thelength of the blade.

The leading and trailing edge members i8 and 20 may be formed by shapingsheet metal to a tubular shape, as shown in Figs. 4 to '7, or may beformed by deforming a tube to the desired shape, in the same manner asthe center section of the blade is formed from the tube ill.

A tube of decreasing outer diameter, as shown in Fig. 8, may be used inplace of the tube of substantially constant outer diameter shown in Fig.1, in which case a blade having a center section of substantiallyconstant width throughout its length will be provided. Such a blade131111.18- trated in Fig. 9, in which the center section 30, which is ofsubstantially constant width throughout its length, has been formed fromthe tube 32 of Fig. 8. Leading and trailing edge portions 34 and 38,respectively, which may be formed in any desired manner such as thosetaught in this application, are attached to the side edge portions ofthe central section.

In Figs. 4 to 7 the leading and trailing edge portions of the blade areshownas formed of tubular parts deformed to the desired shape andattached to the opposite side edge portions of the central section. InFig. 10 of the drawings there are disclosed modified forms of leadingand trailing edge members and a modified form of attachment thereof tothe central section. In this embodiment, the leading and trailing edgeportions 40, 42 are formed of sheet-metal bent to the desired airflowshape. The free longitudinal edge portions of each of these is caused tooverlap the adjacent portions of the upper and lower surfaces of thecentral section and are set into depressions therein. Thus, the freeedges 44, 46 of the leading edge member 40 are received withindepressions 49, 50 in the upper and lower faces of the central section52, which extend along the edges of the central section and the depth ofwhich is made equal to the thickness of the material of the leading edgemember in order to provide a smooth outer surface. The depressions 48,50 are of suflicient extent laterally of the blade to receive enough ofthe edge portions 44, 46 to permit a secure attachment by brazing,welding, riveting or otherwise. The trailing edge portion 42 may, ifdesired, be formed in the same manner as leading edge portion 40 and maybe attached to the center section in the described manner, all asillustrated in Fig. 10.

Each of the embodiments hereinbefore described includes three sections.If desired, a lesser or greater number may be provided without departingfrom the spirit or scope of the invention. Thus, in Fig. 11 a two-partblade is disclosed, having a main section providing the leading edgeportion and the greater part of the center of the blade, and a trailingedge section 82 which, in Fig. 11, is shown as formed and attached tomain section I in the manner illustrated in Fig. 10. Obviously, thetrailing edge section 82 may be formed and attached to the Znainqsectionin the manner illustrated in Figs.

It will be seen that by using any of the constructions described andillustrated, or which may obviously occur to those skilled in the art asvariations within the scope of the invention, a multi-part blade ofproper airflow shape will be provided, and will have internalreinforcing members increasing its strength.

After the blade is completed as described, the surface may be finishedin any desired manner and the blade is then ready for use.

While a number of embodiments-of the invention have been shown anddescribed in detail. it will be understood, that various other changesmay be made and that the described embodiments are illustrative only andare not intended to limit the scope of the invention. reference beinghad for this purpose to the appended claim.

What is claimed is:

A propeller blade comprising a hollow metallic tube of integral sectionformed at one end for connection to a hub and being flattened to formrelatively wide faces of increasing width extending from the hub end ofthe blade to the outer end thereof and which are connected by relativelynarrow side walls, a hollow metallic tube rigidly attached to each sidewall substantially throughout the longitudinal extent thereof, thethree-tubes being of closed cross-sectional shapes and reinforcing andstiffening each other and having such cross-sectional shapes that ateach point along the length of the blade the three cross sectionalshapes combine to provide a desired airfoil shape of the propeller.

HENRY A. BERLINER.

